1. Field of the Invention
The invention relates to a metal can for liquids and more particularly for special liquid formulas for adults and children containing high calorie liquid food providing complete, balanced nutrition, and other similar liquid supplement preparations that must not be contaminated.
More particularly, the invention relates to a can for such liquid products having a can end member which may be opened easily by tearing loose a small generally teardrop or pear-shaped metal area from the flat circular metal panel portion of the can end member to form a pouring spout opening in said panel. The torn out teardrop-shaped metal area and pouring spout opening are defined by an endless score line. A pull tab is riveted to the metal area to be torn from the panel at a zone adjacent the center of the circular panel and the pull tab is used to completely remove the metal area within the score line from the panel.
Further, the invention relates to a metal can end member with a pull tab having nose and ring pull portions with the pull tab nose portion riveted to the circular panel as aforesaid so that the pouring spout opening metal area may be completely removed from the can end member by a person holding the can in one hand and grasping the pull tab ring portion with a finger of the other hand and pulling the ring portion upward and toward the person manipulating the pull tab to open the can.
Also, the invention relates to such a can end member fabricated from light gauge steel to which an aluminum pull tab is riveted and in which the described pulling of the pull tab upward and toward the person opening the can prevents any portion of the metal area being removed from the panel to form the pouring spout opening from entering the can, thereby preventing contamination of the can contents by and during opening of the can.
Further, the invention relates to the described can end construction in which the pull tab structure is weakened in certain locations to permit the described opening procedure to be carried out easily; and in which the pull tab is strengthened in its nose portion to prevent rivet pullout, on the one hand, and to enable bending of the torn out metal area immediately in front of the rivet, on the other hand, to facilitate easy tear-out of the metal area being removed from the panel defined by the endless score line described.
The invention relates further to the new teardrop shape or pear shape of the pouring opening to be formed in the can end, and more particularly to a shape defined by an endless score line which enhances the tear value of the tearing force required to tear the metal area from the can end panel completely to form the pouring opening.
Also, the invention relates to the described can end construction in which the panel of the can end located adjacent the lower end of an annular shouldered countersink wall which extends downward from the out-turned can end flange which is seamed to the upper end of the can side wall, is located so that the pull tab riveted to the central portion of the panel will not move upward beyond the top of the can seam to interfere with processing equipment, when the can filled with the liquid composition is heated during processing of the contents of the can, which causes bulging of the panel.
Further, the rivet connection between the pull tab and panel is enlarged in size, along with pull tab nose strengthening, to increase the strength of the rivet to prevent rivet pull out during pull tab manipulation to provide the pouring spout opening for the can.
Further, strengthening of the panel to maximize the condition of panel flatness and resistance to panel distortion during can opening is provided by a number of downward panel embossments at a number of locations within the flat circular metal panel portion.
One of these is a short straight tip embossment located close to the rivet below the tip of the pull tab to space the embossed valley from the pull tab tip to permit the pull tab to move downward at the beginning of can opening before the tab tip engages the panel metal as the metal within the endless score line is being torn out.
A crescent-shaped embossment is formed in the panel behind the rivet and outside of the semi-circular score line portion that partially surrounds the rivet. This crescent-shaped embossment takes up metal for maintaining panel flatness.
Also, two angularly arranged straight embossments straddle the ends of the crescent embossment which also help to maintain panel flatness.
A thumb embossment is formed in the panel having a horseshoe shape adjacent and extending from the periphery of the panel in a ramplike manner toward the center of the panel beneath the pull ring portion of the pull tab to enable a finger or thumb to be entered below the ring portion of the pull tab for bending the pull tab ring portion upward to start the opening operation.
Finally, a shallow circular beadlike embossment is formed at the periphery of the flat circular metal panel connecting the panel with the lower end of the annular countersink wall portion. This circular bead stiffens the panel which assists in maintaining panel flatness which should be maintained as flat as possible at all times.
The maintenance of flatness in the circular panel and in the area to be torn out within the endless score line is important to provide maximum strength against rupture of the score line if a filled can is accidentally dropped.
2. Description of the Prior Art
There are known steel can ends formed with pouring spout openings for cans containing special liquids as in U.S. Pat. No. 4,399,925, wherein the can is opened in a typical manner with a known type of aluminum pull tab such as shown in U.S. Pat. No. 4,042,144.
However, a need has developed for a pouring spout opening can end construction in which the pouring spout opening may be formed by an individual holding the can in one hand and grasping with a finger or thumb of the other hand a pull tab which may be pulled upward and then forward toward the individual holding the can to completely remove the metal area defined by an endless score line formed in the circular metal can end panel portion.
The described special opening procedure cannot be carried out on a can provided with a can end and pull tab such as shown in said U.S. Pat. Nos. 4,042,144 and 4,399,925, since opening of a pouring spout in a typical manner as shown and described in U.S. Pat. No. 4,399,925 involves pulling the pull tab away from the individual opening the can.
Beverage cans are known in which a drinking opening is formed in a metal can end by tearing metal defining the drinking opening from the can end with a strip metal pull tab riveted at one end to an end of the metal to be torn away at a central location of the can end. This type of beverage can is opened by pulling the pull tab toward the person opening the can. The opening of such a can is quite difficult because of the shape of the flat striplike metal pull tab which normally lies flatwise with full interface surface contact between the pull tab and can end, and because of the magnitude of force required to initiate tearing of the panel metal in a portion of the score line defining the opening, located in the panel at a zone behind the rivet and beneath the strip metal pull tab. Examples of such known construction are shown in U.S. Pat. Nos. 3,204,805 and 3,259,265.
Another can construction shown in U.S. Pat. No. 3,221,924 has various forms of an aluminum opener in elongated strip form having two portions hinged together or otherwise separately relatively movable, one riveted to a panel area of the can end metal which when removed forms a pour opening, and the other riveted to another portion of the can end metal to be removed to form a vent opening. The lever actions of the two-part lever opener in this construction are dependent on first forming the vent opening, and then the pour opening. During manipulation of the flat strip metal opener, the removed metal portion projects into the can during the opening operation.
Another prior art U.S. Pat. No. 3,251,515 protects a preformed pouring opening with an adhesive strip covering the opening. The strip is pulled away to expose the opening. Thus, portions of the protective cover strip do not enter the can during opening, but such construction is not feasible for cans containing special formula foods that are processed in sealed cans by heating.
U.S. Pat. No. 3,322,296 shows another known construction of metal pull tab having a reinforced nose portion and a full circular ring portion connected by a narrow metal bendable hinge portion. The pull tab nose is riveted to the can end panel adjacent a full opening circular score line formed in the panel. The pull tab bends during the opening operation during which a portion of the can end panel is projected into the container when the score line is ruptured to initiate tearing of the circular panel portion completely from the can end.
None of the various prior art devices described have any construction which satisfies present requirements set forth in detail above for a can end construction for special liquid food products which must not be contaminated and which may be contained in a can provided with a steel can end with an aluminum pull tab manipulated by pulling the pull tab upward and then toward the individual holding the can to completely remove the metal area from the panel to form a pouring opening without any of the removed metal entering the can at any time during opening.
Accordingly, there is an existing need in the art for a can for special liquid food products heat processed in a sealed can provided with a steel can end which may be opened easily with an aluminum pull tab riveted to the can end panel generally centrally of the panel, which pull tab may be manipulated in the manner described to completely remove the metal area from the panel to form a pouring opening defined by an endless score line without contaminating the contents of the can by projecting any part of the pull tab or removed metal portion into the can during opening.